I never intensely wrote about viruses on this blog, basically because I am no expert in viruses. I have loads of them in my computer, some actually ended up messing up with my hard-drive so badly that I had to purchase a brand new one. Recently, I got to stay in bed for a week with a stupid Influenza variation that ruined my energy and reduced me to tears. I survived both events, the computer infection and the flue one. But as I rise from the death to go back to my thesis writing and job hunting, as I always do every single morning after dropping off my little one in the nursery, the world announces me that I shall not rest my defenses for another virus is coming.
Some time ago there was Ebola. The cacophony of its name actually makes me laugh and it is such an interesting virus that can trigger many plot ideas for cinema motion pictures. But we apparently survived that. Far before that we had A type Influenza, the hens and the pigs were conspiring to take over what had been rightfully owned by the human race. We managed to survive that. But now there is something worse, something that does not want to mess up with the birds and the Suina, doesn't want to emerge from the tombs of African forests, it comes from the sunny landscapes of South America with more Sambuca than Samba, and is making our heads spin with its transmission features.
Because I am not a virus expert I'd like to understand the basics before jumping to the hard matter on the news. And when everyone is talking about how Zika, this new virus from the warm pastures of South America, can make the human babies suffer of microcephaly, well!... You want to know all there is to know. So I thought that for those who struggle like me in understanding a few of the basics that reporters so intelligently babble in Nobel-Prize-type-short-interventions, why not compiling a few bits of info first:
In what consists a virus?
Viruses are obligate intracellular parasites and can only reproduce inside a host cell. They consist of nucleic acids enclosed in a protein coating and eventually a membranous envelope. Viruses do not possess enzymes to degrade stuff or ribosomes to produce proteins. They are like transposons that travel around the genome like Harley Davidson easy-riders.
How does a typical virus look like?
Viruses carry DNA or RNA?
They can carry single stranded or double stranded, RNA or DNA!, and that is what actually defines their nomenclature... RNA virus or DNA virus.
Do they only infect people?
They can also infect animal, plants and bacteria (these are quite complex in nature and structure).
Why is that they kill the cells?
Because for viruses to reproduce they use lytic and lysogenic cycles. The lytic cycles are typical of the strongest viruses, usually kill the host cell and are accompanied by a very adaptable genome that fights restriction nucleases bacteria might produce. The lysogenic cycles consist on softer processes where the host cell is not destroyed. Some phages can actually use both reproductive systems.
What are viruses looking for in the host cells?
The very same we humans look everywhere, the right conditions to survive and have fun. The host cell provides energy in the shape of ATP, also amino acids, ribosomes and enzymes the virus doesn't have, and the good old nucleotides (the building blocks of the nucleic acid production that also sustain the very nature of virology).
Why do some viruses reappear?
Well some are just very good in keeping dormant until the right conditions are set for them to show up again, like the herpes virus. The herpes virus has an envelope deriving from the nuclear membrane, it becomes integrated in the host cell genome as a provirus and when the right stressful situations occur, the virus emerges for the festival. The main route of infection is propelled by the envelope of the virus that can attach and invaginate in the cell membrane lipid bilayer, then the endoplasmatic reticulum of the cell will provide proteins that only help the cell get worse and worse.
Is there a virus hardcore division, like the real bad guys?
Ohhh yesss! The retroviruses have been the Grim Reaper of rock stars from the early 80s like mad killers. These are more complicated to explain because their genetic information flow in the reverse direction!
What are the Premier League and the
Conference Leagues of Viruses in animals?
Check the image below and you will have your answer.
How do viruses actually destroy the cell?
Essentially in three major ways: 1) some by telling the host cells to release hydrolytic enzymes, 2) some by telling the host cells to produce toxins that promote disease, and 3) others already have these toxins in their envelopes and just need to deliver the bad messages straight in.
Is there any other smaller type of viruses?
Yes, shall we call it the Tiny Tiny Division, constituted by Viroids and Prions. Viroids are smaller and simpler than viruses and typically infect plants. Prions are proteinaceous infectious particles and became famous in the 90s for driving cows very very mad crazy!
Great!, I didn't really tell you anything special about the Zika virus, but in all honesty you know more about it now than you knew before. And that was to build a foundation, the rest will unfold as the world unzips the Zika virus... at least until something more fashionable gets the attention of the media.